776 PAEASITIC DISEASES. 



only necessary to add that the labours of Steenstrup, Leuckart, 

 Van Beneden, Pagenstecher, Moulinie, Davaiue, Pilippi, and 

 Simonds have played a most conspicuous part. It may also 

 be observed that, notwithstanding many assurances to the 

 contrary, the present state of our knowledge does not justify 

 our going beyond the data and conclusions here given. The 

 statement made by one naturalist, to the effect that the larvse of 

 the common fluke reside in the mollusc called Succinea putris, 

 has not received confirmation. That the larvse are not limited 

 to a single species of molluscan bearer is, to say the least, 

 extremely probable. All things considered, perhaps the follow- 

 ing may, in the present state of the science, be regarded as 

 a fair exposition of the genetic relations and phenomena ex- 

 hibited by the common liver fluke. 



1. The liver fluke, in its sexually mature state (Distoma 



hepaticum) gives rise to the disease commonly called o^ot ; 

 this affection being also locally termed coathe (Dorsetshire, 

 Devon), ilcs (Cornwall) and hane (Somersetshire). In 

 France it is known as the Cachexie aqueuse, and more 

 popularly as pourriture. In Germany the epidemic 

 disease is called egclseuche, and in a more limited sense 

 either die Fdule or die Lcberkrankheit. 



2. The rot is especially prevalent during the spring of the 



year, at which time the fluke itself, and innumerable 

 multitudes of the free eggs, are constantly escaping from 

 the alimentary canal of the bearer. The germs are thus 

 ordinarily transferred to open pasture-grounds, along with 

 the faeces of the bearer. 



3. As it has been shown by dissections that the liver of a 



single sheep may harbour several hundred flukes, and as 

 also a single adult fluke is capable of throwing off several 

 thousand eggs, it is certain that any rot-affected flock is 

 capable of distributing millions of fluke germs in the egg 

 condition. 



4. Such flukes as have accidentally escaped their host per 



anum do not exhibit powers of locomotion sufficient to 

 enable them to undertake migrations. Their slight 

 movements, however, subserve the purpose of concealing 



